1. Field of the Invention
The present invention relates to a transmitting system for a small-sized vehicle such as a two-wheeled motor vehicle and a buggy, and particularly to an improvement in a transmitting system for a small-sized vehicle, in which a centrifugal clutch and a torque converter are interposed in series between a crankshaft of an engine and an output gear relatively rotatably carried on the crank shaft.
2. Description of the Related Art
Such a transmitting system for a small-sized vehicle is already known as disclosed in, for example, FIG. 17 of Japanese Patent Application Laid-open No. 2000-213627.
This transmitting system for a small-sized vehicle prevents drag of a small-sized vehicle caused by creep of a torque converter due to the disengaged state of a centrifugal clutch during idling of an engine, and at the time of start and acceleration, the transmitting system can perform smooth power transmission and torque amplification by cooperation between the centrifugal clutch and the torque converter.
In such a conventional transmitting system for a small-sized vehicle, a drum of the centrifugal clutch is spline-coupled to a diving plate connected to a crankshaft, its open surface is made adjacent to a pump impeller of the torque converter, and a clutch output member disposed inside this drum is splin-fitted to a hub of the pump impeller.
In such a conventional transmitting system, the drum at the outermost side has to be removed in the process of the maintenance of the centrifugal clutch, and therefore it cannot be said that favorable operability is provided. In addition, since the pump impeller and the clutch output member are independent components which are spline-coupled to each other, it is necessary to work the spline coupling portions of both of them with high precision to prevent rotation vibrations and unusual noises by eliminating play between them while securing concentricity of the pump impeller and the clutch output member. Moreover, the transmitting system involves large numbers of components and assembling steps, the conventional transmitting system is also disadvantageous in terms of cost reduction.